1. Field of the Invention
The present invention relates to a stator of a rotating electric machine that can be preferably used for a polyphase generator and the like, and more specifically relates to improving a connection device of a stator coil end.
2. Description of the Related Art
As a stator of a conventional rotating electric machine, a stator is given, in which a stator coil to be inserted into a slot of a stator iron core is configured by four wire groups, and when the four wire groups are collectively connected at a coil end, which is projected from a slot end in an axial direction of a rotor, a large circulating current flows between the wire groups, therefore the wire groups are divided into two wire groups each, and a conductive block is used to connect between the two wire groups at a stator coil end respectively, and the respective, two wire groups are separately connected to another stator coil in the slot in a radial direction by a connection conductor. The connection conductor is provided on outer side faces of the wire groups (for example, refer to U.S. Pat. No. 7,088,020 (p1, FIGS. 1 and 6) and JP-A-6-14483 (p1, FIG. 3)).
In the previous stator of a rotating electric machine configured as above, the conductive block was necessary to be provided for electrically connecting between the divided, two wire groups adjacent to each other at the stator coil end. In addition, since the connection conductor was provided on outer side faces of wire groups, the connection conductor connecting the stator coil end, which was collectively connected by the conductive block, to another stator coil in a slot for the respective, two wire groups, the connection conductor and the conductive block were doubly present in a circumferential direction in the relevant connection portion, leading to a problem that material usage was increased. Moreover, the conductive block and the connection conductor were present in the stator coil end in this way, leading to a problem that weight was increased, which was disadvantageous in vibration suppression. Moreover, since a current largely flows through a region approximately 10 mm (penetration depth) inside the connection conductor due to reduced electric resistance and the skin effect, significant loss occurs at a stator iron core side of the connection conductor. In the previous structure as above, since a heat path for cooling the connection portion is long, including a path from the connection conductor to the conductive block via a bonding surface between the connection conductor and wire groups, the wire groups, and a bonding surface between the conductive block and the wire groups, thermal resistance is increased, which causes high temperature, leading to a possibility that an insulative material applied to a tip of the stator coil end was degraded. This led to a problem that a current was restricted in current carrying.